By now, you're probably familiar with the (many) ways to score flight deals: Compare booking sites. Be flexible with your dates and airports. Subscribe to flight deal blogs, set price trackers, and get over the myth that there's one perfect day to book that flight to Buenos Aires. But starting today, there's a new way to knock hundreds off airfares—and it's a good one.

Hopper, whose free mobile-only app scouts the cheapest fares and predicts ticket prices, just released its "Secret Fares" feature. The result of a partnership with Air Canada, LATAM, Turkish, WestJet, Copa, and Air China, the deals cover 60,000 routes, aren't available anywhere else online, and can be up to 35 percent cheaper than the same ticket elsewhere. (A spokesperson for Hopper says there will be more airlines, including domestic ones, joining the Secret Fares program, but that the company can't disclose any more information at the moment.) For now, all you have to do is download the app, "watch" a trip, and you'll get the notifications right to your phone: Just think of it as a personalized flight deal, delivered to the palm of your hand.

With Secret Fares, Hopper will show you exclusive deals you won't find anywhere else.

Courtesy Hopper

In beta-testing, Hopper users certainly saved. A flight from Miami to Madrid was selling online for $1,083 round-trip, but a "Secret Fares" price came in at $864. Dallas to Beijing? $1,375 online, but nabbed for $864. Chicago to Tokyo: $1,422 vs. $1,152. You get the picture.

The benefit here isn't just for the travelers—this approach helps participating airlines, too. Typically, when a carrier cuts prices online, they're often matched in an "airfare war" with other airlines within a few hours, and that pool of potential customers then becomes a lot smaller. But put those prices only on Hopper—an app with 20 million installations since its launch in 2015, and 95 percent "buy or wait" accuracy—and that problem is solved. It's so smart we're not sure why no one thought of it sooner.